Ten Things You Need to Know About Your Roof


Putting a roof over your head is not a one-and-done deal. Roofs not only stand between you and the elements, but they are part of the overall structural support of your home. We’ve compiled a list of frequently asked questions with answers that will help you keep a good roof over your head.

  1. What are the factors that have an effect on the durability and longevity of roof shingles?
  • The side of your roof that faces the worst weather is the side where the shingles will fare the worst.
  • A low pitched roof that collects leaves and debris that hold moisture against shingles will deteriorate faster due to the growth of moss and algae.
  • The sun’s rays are extremely hard on the side of a roof that get the sun’s full impact.
  • A roof that is vented properly will have a longer life span than one where heat builds up beneath the roofing.


  1. What is the best underlayment to protect a roof from leaking?


A good roofer will place an ice and water shield over the entire roof which is a polyethylene and rubberized product. It keeps water that has worked its way under shingles from getting inside the house. It is recommended to have two layers of this ice and water shield on the lowermost sections of a roof near the eaves and also along dormers and chimneys.


  1. What is the purpose of felt paper used on a roof?

Black felt paper comes in long rolls and is used as a barrier between shingles and the plywood layer which is installed on roof rafters. At one time, sap used to leech out of the wood and it would destroy the underside of asphalt shingles, hence the need for a protective barrier. The use of engineered plywood has negated the need for this protective layer. Now it is used as another layer of water protection just in case your shingles blow off in a storm to keep rainwater out of your attic.


  1. What are the black streaks that appear on my roof shingles?

The black streaks are caused by algae that live and feeds off of minerals in some types of shingles. To remove these streaks, use one part bleach to two parts water in a garden pump sprayer and apply to the entire roof. Make sure you protect foundation plantings with a tarp before you start as bleach can kill these plants. Safety first: make sure you do this from the ground or a ladder, not standing on your roof.

There are certain shingles that come with algae-inhibiting granules so the next time you need to reroof your home, look for this feature.


  1. How many layers of shingles are acceptable on a roof?

Because of the weight of shingles, professionals advise just one layer. So if your home needs a new roof, make sure the contractor knows to take off the existing layer. Many pros will advise that two layers are the most any roof structure should support, but one is the preferred number. Usually you will see two layers close to your gutters – this is normal as the starter course for shingles is usually two thick then tapers to one layer all the way up to the roof ridge.

  1. Is there a way to tell when your home needs a new roof?

The easy way to know if your home needs a new roof is if the roof is approaching 20 years old. Most shingles will need replacing when they get to that age.

Younger roofs can fail, too, so it is advised that you check your roof once a year. This can be done from the ground with a pair of binoculars. Look for shingles that have curled edges, lifting up, cracking or are missing. If shingles are smooth, then the granules have worn off and this is a sign that the roof has outlived its useful life.   A visit to your attic on a sunny day will reveal places where light is shining through and if widespread, it is a good indication that your shingles are failing. Also, the underside of your roof will show several wet areas after a rainstorm if your roof needs replacing.

  1. What shingles are best?

Generally, the longer the warranty on shingles, the better they are. Similarly, heavier shingles last longer and cost more.


  1. How do you keep cedar shakes looking light and new without ruining their Class C fire rating?

All wood will turn grey over time so it is not possible to keep that just-new look of cedar shingles and shakes. Keeping your roof clean will do the most to preserve the longevity of the cedar and keep moss from growing on the shingles. If you want to add a preservative treatment to your roof, make sure that the chemicals are compatible with the fire retardant that is applied to the individual shingles during their manufacture. These chemicals will provide UV protection, water repellency and a wood preservative.


  1. Are there any special considerations when using natural or synthetic slate shingles?

Both types of slate shingles are pretty smooth and will release large avalanches of snow at once. These snow shifts can damage gutters, porch roofs and pedestrians who may be passing under the roof at an inopportune moment. If you are considering a slate roof, real or synthetic, you will want to install snow guards which will contain the snow in one place, away from the eaves, so that it melts slowly in place instead of discharging all at once.

  1. How can you stop the frost on the nails that protrude through the roof in your attic?

When the temperature is cold, as we experience here in Lincolnshire in the winter, warm air from the inside of your home escapes into the attic and condenses on the steel nail tips. It freezes immediately upon hitting the cold metal. This is a problem not just for the nails, but it can encourage mold growth in your attic and lessen the insulating power of your attic insulation. To fix this issue, you need to seal the interior of your home from the attic better. Use a thermographic imaging camera to detect the places that moist interior air is leaking into your attic. Also check to make sure your attic is vented properly and that the vents are not blocked by snow or loose insulation.